John Williams Walker (August 12, 1783 - April 23, 1823) was an American politician, who served as the Democratic-Republican United States senator from the state of Alabama, the first senator elected by that state. Walker was born April 23, 1783 in Amelia County, Virginia, of Scotch-Irish heritage, the son of Rev. Jeremiah Walker and Mary Jane Graves. He was educated at the prestigious academy of Dr. Moses Waddell at Petersburg, Georgia, and received degrees in 1806 and 1809 from Princeton University. He studied law, and was admitted to the bar at Petersburg.
In 1808, Walker married Matilda Pope, daughter of LeRoy Pope and Judith Sale, and in 1810, he followed his father-in-law to settle in the new town of Huntsville, Mississippi Territory (now Alabama), and there began the practice of law.
Upon the formation of the Alabama Territory in 1817, Walker served as a representative from Madison County to the first territorial legislature in 1818. In the second session, he served as speaker. In 1819, he was president of the convention that framed Alabama's first constitution, which enabled Alabama's admission to the United States.
On October 28, 1819, Walker was elected by an almost unanimous vote of the state legislature as the first United States senator from Alabama. He served from December 14, 1819 until his resignation on December 12, 1822 on account of his failing health. He died in Huntsville on April 23, 1823, and is buried in Maple Hill Cemetery. Walker County, Alabama, established December 26, 1823, is named in his honor.
Walker was the father of LeRoy Pope Walker, Confederate secretary of war and brigadier general; Richard Wilde Walker, Confederate States senator; Percy Walker, United States representative; and several other children.